Rehabilitation of RC-inverted-T bentcarp girders using CFRP sheets

Abstract

Existing infrastructure includes significant number of reinforced concrete (RC) bridges that are old and designed based on outdated design codes. Inverted-T beams used as bentcap girders that support the bridge's longitudinal precast beams provided a popular structural system of many existing bridges. The structural behaviour of inverted-T beams is different than that of conventional top-loaded beams, due to the fact that the loads are introduced into the bottom flange rather than the top of the beam. The objective of the present study is to experimentally examine the effectiveness of new rehabilitation techniques using anchored carbon fibre-reinforced polymer (CFRP) sheets to eliminate non-ductile failure mechanisms in hanger, web, and flange zones of RC inverted-T girders, and to analytically evaluate the effect of design variables on the failure mechanisms of FRP-rehabilitated RC inverted-T bentcap bridge girders. The experimental phase of this study included conducting eight tests on four simply supported RC inverted-T girders before and after rehabilitation. The girders represent a 1/3 rd scale model of a prototype bentcap girder. The experimental results showed that the proposed new rehabilitation schemes proved to eliminate the non-ductile mechanisms in hanger, web, and flange zones. The rehabilitated girders were able to reach displacement ductility levels of up to 4 and showed an increase in strength up to 20% compared to the control girders. The analytical phase of this study included conducting a parametric study on the effect of the uncertainties in the design variables on the failure mechanisms of an existing RC inverted-T bridge bentcap girder rehabilitated using externally bonded FRP sheets. The analytical study identified the design variables that are directly- or indirectly-proportional to the required content of FRP wraps that is needed to ensure a ductile response, which is useful for design engineers of rehabilitation schemes that uses externally-bonded FRP sheets